Many people ask about the ECU reset. What does it do? Is it really worth doing? Are there any negative effects? I think it's time to have a definitive guide to the ECU reset.

Why do we reset the ECU's?
The main reason we reset the ECU's in our cars is for more power. Plain and simple. Why? After a little while of driving, the ECU de-tunes the engine to satisfy the O2 needs of the cat. When you reset the ECU, it resets the fuel maps to a base value that's more suited to power.

Is this bad in any way?

Yes, it can be harmful. When you reset the ECU it changes the fuel maps, which is potentially harmful to the cats.

How often should I do it?

Only when you need the extra power. If you are going to race, dyno, or show off, these are the only times you should do the reset from a power standpoint.

How do I reset the ECU?

There's multiple theories about this. The time consuming way is to disconnect the negative battery terminal for 15 minutes, press the brake pedal, then reconnect the negative terminal. This method is fine if you want to wait around 15 minutes, and reset the clock, and the radio presets and settings. A simpler way is to pull the two fuses labeled "ECU" in the underhood fuse block. And the easiest way (after initial difficulty) is to hook up a switch; ECU reset switch DIY